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The South American tomato leafminer, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is an invasive Neotropical pest. After its first detection in Europe, it rapidly invaded more than 30 Western Palaearctic countries becoming a serious agricultural threat to tomato production in both protected and open-field crops. Among the pest control tactics against exotic pests, biological control using indigenous natural enemies is one of the most promising. Here, available data on the Afro-Eurasian natural enemies of T. absoluta are compiled. Then, their potential for inclusion in sustainable pest control packages is discussed providing relevant examples. Collections were conducted in 12 countries, both in open-field and protected susceptible crops, as well as in wild flora and/or using infested sentinel plants. More than 70 arthropod species, 20 % predators and 80 % parasitoids, were recorded attacking the new pest so far. Among the recovered indigenous natural enemies, only few parasitoid species, namely, some eulophid and braconid wasps, and especially mirid predators, have promising potential to be included in effective and environmentally friendly management strategies for the pest in the newly invaded areas. Finally, a brief outlook of the future research and applications of indigenous T. absoluta biological control agents are provided.  相似文献   
2.
Suppression of microRNA-silencing pathway by HIV-1 during virus replication   总被引:1,自引:0,他引:1  
MicroRNAs (miRNAs) are single-stranded noncoding RNAs of 19 to 25 nucleotides that function as gene regulators and as a host cell defense against both RNA and DNA viruses. We provide evidence for a physiological role of the miRNA-silencing machinery in controlling HIV-1 replication. Type III RNAses Dicer and Drosha, responsible for miRNA processing, inhibited virus replication both in peripheral blood mononuclear cells from HIV-1-infected donors and in latently infected cells. In turn, HIV-1 actively suppressed the expression of the polycistronic miRNA cluster miR-17/92. This suppression was found to be required for efficient viral replication and was dependent on the histone acetyltransferase Tat cofactor PCAF. Our results highlight the involvement of the miRNA-silencing pathway in HIV-1 replication and latency.  相似文献   
3.
Agroforestry Systems - Sustainable forest management is proposed as a solution for many ecological and socio-economic trade-offs associated with different forest uses. In Patagonia, silvopastoral...  相似文献   
4.
Allium ampeloprasum evolved as a complex of different cyto- and morpho-types widely distributed either in the wild or domesticated range of the Mediterranean regions. The assessment of genetic and phylogenetic relationships between Tunisian A. ampeloprasum and specimens from different origins and with variable degree of domestication can promote conservation and breeding. Minisatellite M13, microsatellite (GTG)5 and nucleotide sequence analysis of the internal transcribed spacer region (ITS) were used to assess DNA polymorphism and genetic diversity. M13 and (GTG)5 molecular markers efficiently discriminated A. ampeloprasum gene-pool from A. sativum. Geographic genetic patterns of variation of the wild gene-pool were not detected. However, domesticated A. ampeloprasum (great headed garlic, kurrat and leek) clustered consistently within the ampeloprasum group. A. sativum was found to be closer to A. ampeloprasum than A. fistulosum and A. schoenoprasum. A high number of single point mutations (SNPs) was recorded over the ITS1-2 spacer sequence. Most of these SNPs were heterozygous only in great headed garlic. It is inferred that heterozygosity played the major role in promoting great headed garlic domestication. Thus, great headed garlic adaptation to horticultural conditions along with its yield trait sizes are mainly associated to heterozygosity rather than to polyploidy.  相似文献   
5.
A large‐scale survey of Citrus tristeza virus (CTV) was carried out from 2016 to 2018 in the Chlef Valley, one of the main citrus growing areas in Algeria. In this study a total of 1680 citrus trees from 93 commercial orchards were sampled. The collected samples were tested by direct tissue blot immunoassay analysis and by the double antibody sandwich enzyme‐linked immunosorbent assay technique, and 54 trees were identified as being infected with CTV. This result confirmed that 54 trees were infected by the virus, corresponding to an infection rate of 3.21% throughout the studied area. Five of these local CTV sources were chosen for further molecular investigations to determine the genotype associated with the CTV isolates now spreading in the Chlef area. Characterization with multiple molecular markers showed the presence of the T30 and VT genotypes. This result allowed confirmation of the presence of a virulent strain belonging to the VT genotype. The other CTV isolates were similar to those from the Mitidja region, which showed 99% nucleotide identity with the Spanish mild CTV isolate. This early finding of a strain belonging to the VT genotype is an issue for Algerian citrus producers and needs rapid actions to be taken by the National phytosanitary services, extending the surveillance to other citrus production regions and uprooting the infected trees.  相似文献   
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7.
One hundred and eight isolates of Phytophthora infestans were collected from infected potato and tomato crops in the middle-north of Morocco during 1997–2000. Pairings of these isolates with tester isolates of mating type A1 and A2 revealed that 60% of the isolates were mating type A2 (65/108) and 40% were mating type A1. After 10 days incubation at 20 °C and a 16-h photoperiod, approximately 25% and 18% of the oospores produced in-vitro germinated in potato soil extract and potato root extract, respectively. Oospores were observed in potato leaf tissues in pairings that were fertile in-vitro. Maximum production of oospores was obtained in potato leaves of cultivars that were moderately susceptible (Desirée, Nicola) after 10 days of incubation at 15 °C and a 16-h photoperiod. These results confirm the presence of P. infestans strains that are sexually compatible under Moroccan climatic conditions. Production of oospores constitutes a threat for these crops because of the occurrence of recombinants with new virulences which may be difficult to control and as a consequence survival of oospores in absence of the host plant in the soil.  相似文献   
8.
Y. Guenaoui 《EPPO Bulletin》2010,40(2):193-195
Une population établie de Tetranychus evansi a été signalée pour la première fois sur cultures de tomate dans le nord‐ouest de l’Algérie. Des données sur l’origine, la répartition géographique actuelle, l’identification et les plantes‐hôtes sont également présentées.  相似文献   
9.

Key message

Soil texture and temperature-related variables were the variables that most contributed to Nothofagus antarctica forest height in southern Patagonia. This information may be useful for improving forest management, for instance related to the establishment of silvopastoral systems or selection of suitable sites for forest reforestation in southern Patagonia.

Context

Changes in forest productivity result from a combination of climate, topography, and soil properties.

Aims

The relative importance of edaphic and climatic variables as drivers of productivity in Nothofagus antarctica forests of southern Patagonia, Argentina, was evaluated.

Methods

A total of 48 mature stands of N. antarctica were selected. For each study site, we measured the height of three mature dominant trees, as an indicator of productivity. Seven soil, five spatial, and 19 climatic features were determined and related to forest productivity. Through partial least squares regression analyses, we obtained a model that was an effective predictor of height of mature dominant trees in the regional data set presented here.

Results

The four variables that most contributed to the predictive power of the model were altitude, temperature annual range, soil texture, and temperature seasonality.

Conclusion

The information gathered in this study suggested that the incidence of the soil and temperature-related variables on the height of dominant trees, at the regionally evaluated scale, was higher than the effect of water-related variables.
  相似文献   
10.
The mealybug Phenacoccus madeirensis Green (Hemiptera: Coccomorpha: Pseudococcidae) is recorded from Algeria for the first time. This pest was first detected in the summer of 2018 in private gardens in Salamandre, on the coastal side of Mostaganem City in north‐western Algeria, feeding on three ornamental plants: Hibiscus rosa‐sinensis L., Hibiscus syriacus L. (Malvaceae) and Cestrum nocturnum L. (Solanaceae). In October 2018, it was also found on Aloysia citriodora Palàu (Verbenaceae) growing near Hibiscus. The first samples collected had been attacked by hymenopteran parasitoids. Surveys of ornamental nurseries and greenhouses growing vegetables in the area indicate that, at present, P. madeirensis seems to be restricted to ornamental plants. More surveys over larger areas are needed to determine its distribution and the likely origin of its introduction to Algeria.  相似文献   
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